Carbon/carbon (“C/C”) parts are employed in various industries. An exemplary use for C/C parts includes using them as friction disks such as aircraft brake disks, race car brake disks, clutch disks, and the like. C/C brake disks are especially useful in such applications because of the superior high temperature capability, light weight, stable friction performance and/or other characteristics of the C/C material. In particular, the C/C material used in C/C parts such as aircraft brakes is a good conductor of heat and thus is able to dissipate heat away from the braking surfaces that is generated in response to braking. C/C material is also highly resistant to heat damage, and is thus capable of sustaining friction between brake surfaces during severe braking, without a significant reduction in the friction coefficient or mechanical failure.
C/C material is generally formed by utilizing continuous carbon fiber or oxidized polyacrylonitrile (PAN) fibers, referred to as “OPF.” Such OPF fibers are the precursors of carbonized PAN fibers and are used to fabricate a preform shape using a needle punching process. OPF fibers are layered in selected orientations into a preform of a selected geometry. Typically, two or more layers of fibers are layered onto a support and are then needled together simultaneously or in a series of needling steps. This process interconnects the horizontal fibers with a third direction (also called the z-direction). The fibers extending into the third direction are also called z-fibers. This needling process may involve driving a multitude of barbed needles into the fibrous layers to displace a portion of the horizontal fibers into the z-direction.
In typical OPF preforms used for production of aircraft brake preforms, z-fibers are created by transferring in-plane fibers into the z-direction by needling. Z-directions fibers are created due to the high elongation characteristics of the OPF. OPF maintains elongation values in the range of 12-14%. Carbon fibers on the other hand have elongation values that are typically less than 1%. Thus, needling operations do not effectively create a z-fiber; carbon fibers break well before a z-fiber is created. Higher needling levels can be employed however higher needling tends to break up the carbon fibers thus reducing in plane mechanical properties and negatively impacting friction and wear properties. Methods have been employed to incorporate short fiber mats or discontinuous fiber forms into the preform to facilitate z-fiber transfer but these require a second fiber form which increases fabrication cost and complexity.
A circular needle loom may be utilized to form a circular preform, for example, for use in creating carbon brake disks. Various textile technologies exist for fabricating continuous fiber feed forms for a circular needle loom, including yarn placement, stitch bonding, pre-needling, and loom weaving with conical take-up rolls. Narrow fabric or other weaving looms may be utilized to produce a continuous spiral textile tapes to be utilized in a circular needle loom to form a circular preform. These spiral textiles may contain circumferential fibers that lie along the length of the textile, and off-axis fibers that lie along the width of the textile.
Significantly, prior art systems and methods for manufacturing circular preforms suffer from inefficiencies in the manufacturing process. For example, the needling process often tears and breaks up fibers and while displacing fibers may inadequately entangle the fibers to create a preform having desired strength properties.